Which of the following electronic configuration represents a sudden large gap between the values of second and third ionisation energies of an element?

Options

A. `1s^(2),2s^(2)2p^(3)`
B. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(3)`
C. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(1)`
D. `1s^(2),2s^(2)2p^(6),3s^(2)`

Answer

To determine which electronic configuration represents a sudden large gap between the second and third ionization energies of an element, we need to analyze the stability of the electronic configurations after the removal of electrons.

### Step-by-Step Solution:

1. **Understand Ionization Energy**: Ionization energy is the energy required to remove an electron from an atom. A large gap between the second and third ionization energies indicates that the removal of the third electron comes from a more stable electron configuration.

2. **Analyze Each Configuration**:
- **Configuration 1: 1s² 2s² 2p³**
- 1st Ionization: 1s² 2s² 2p²
- 2nd Ionization: 1s² 2s² 2p¹
- 3rd Ionization: 1s² 2s² 2p⁰
- The removal of the third electron does not come from a stable configuration (it is neither half-filled nor fully filled), so the gap is not large.

- **Configuration 2: 1s² 2s² 2p⁶ 3s² 3p³**
- 1st Ionization: 1s² 2s² 2p⁶ 3s² 3p²
- 2nd Ionization: 1s² 2s² 2p⁶ 3s² 3p¹
- 3rd Ionization: 1s² 2s² 2p⁶ 3s² 3p⁰
- Again, the third electron is removed from a non-stable configuration, so the gap is not large.

- **Configuration 3: 1s² 2s² 2p⁶ 3s² 3p¹**
- 1st Ionization: 1s² 2s² 2p⁶ 3s²
- 2nd Ionization: 1s² 2s² 2p⁶ 3s¹
- 3rd Ionization: 1s² 2s² 2p⁶
- The third ionization involves removing an electron from a stable, fully filled configuration (2p⁶), so the gap is not large.

- **Configuration 4: 1s² 2s² 2p⁶ 3s²**
- 1st Ionization: 1s² 2s² 2p⁶ 3s¹
- 2nd Ionization: 1s² 2s² 2p⁶ 3s⁰
- 3rd Ionization: 1s² 2s² 2p⁶
- The removal of the third electron comes from a fully filled 2p orbital, indicating a very stable configuration. Thus, the energy required for the third ionization will be significantly higher, resulting in a large gap between the second and third ionization energies.

3. **Conclusion**: The electronic configuration that represents a sudden large gap between the values of second and third ionization energies is **1s² 2s² 2p⁶ 3s²** (Option 4).